360 AGRICULTURAL BACTERIOLOGY. 



among the animals examined in the slaughter houses of Den- 

 mark it has sometimes appeared that more than half of the 

 cows are tuberculous. From these high figures the percentage 

 has ranged down to 10 per cent., and even lower in some cases, 

 and, in fact, is so variable that no general averages are of 

 any significance. In the United States the results differ so 

 widely that figures have, as yet, little value. Sometimes every 

 animal in a herd is found to be tuberculous, while again other 

 whole herds are entirely exempt. In the western states the 

 amount is small. In the eastern states it is large, and in some 

 cases appears to approach the figures given for Denmark. One 

 may find in different localities averages all the way from 6 

 per cent, to 30 per cent, or higher. When the numbers of in- 

 fected animals in a herd range from o to 100 per cent., it is 

 evident that no average that might be made would be of any 

 significance. 



Increase of the Disease. The next question of vital interest is 

 whether bovine tuberculosis is on the increase. The extreme 

 significance of this question to the agricultural industry is so 

 evident that it needs no comment. Upon its answer seems to 

 depend the future of the dairy industry. For if, as has been 

 claimed, it is rapidly increasing, the very existence of the dairy 

 industry is threatened. But here again statistics are so uncertain 

 as to make a conclusion difficult. Certainly we hear much more 

 of the disease than we did a few years ago, and certainly the per- 

 centages reported to-day are much higher than they were ten 

 years ago. The knowledge of the disease is, however, of 

 very recent date, and it has only been in the last few years 

 that its full import has been felt. The increasing interest in 

 the subject has caused a more and more careful inspection 

 of slaughtered animals, which has resulted in a constant in- 

 crease in the number of reported cases. Even in the same 

 slaughter houses and under the same management the per- 

 centage of tuberculous animals reported has been increasing 



